ML19319A765

Ro:On 721230,1B2 Reactor Coolant Pump Motor Oil Leaked & Fire Resulted.Caused by Gasket Failure in Oil Lift Pump Circuit.Gaskets Replaced & Overflow Line Installed

ML19319A765
Person / Time
Site:	Oconee
Issue date:	12/30/1972
From:	DUKE POWER CO.
To:
Shared Package
ML19319A763	List: ML19319A764 ML19319A765
References
NUDOCS 7912040666
Download: ML19319A765 (3)

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DUKE POWER COMPANY

.- OCONEZ NUCLEAR STATION UNIT 1 132 Reactor Coolant Pu=p Motor 011 Leak and Fire Dece=ber 30, 1972 1.0 SUMARY OF CCCURRENCE A gasket failure occurred on a high pressure oil line flange in the oil lif t pu=p circuit for the 132 Reactor Coolant Pu=p Motor. Oil leaked onto the pu=p casing, and between the pu=p casing and inlet piping and the Mirror insulation installed at these points. The Reactor Coolant System was in an elevated te=perature con-dicion at the time due to the fact that Hot Functional Testing was in progress and, as a result, the leaking oil ignited upon contact with the hot pu=p casing and inlet piping. The fire was extinguished by operating personnel and, following cooldown of the Reactor Coolant Systen, an investigation was conducted and appro-priate cleanup and repairs performed.

2.0 SEQUENCE OF EVENTS On Dece=ber 30,'1972, Hot Functional Testing was in progress at Oconee Nuclear Station, Unit 1, however there were no particular tests being conducted that ralated to this incident. The Reactor Coolant System was at a te=perature of approximately 532*F resulting from operation of the Reactor Coolant Pumps.

The sequence of events preceding the occurrence of the fire, as indicated by a co=puter printout, is as follows:

0545.47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br /> 132 011 Lift Pu=p On 0545.49 hours5.671296e-4 days <br />0.0136 hours <br />8.101852e-5 weeks <br />1.86445e-5 months <br /> 132 011 Lift Pu=p Discharge Nor=al.

0551.33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> 132 Reactor Coolant Pu=p On 0551.47 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br /> 132 Reactor Coolant Pu=p 100% Speed 0551.54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> 132 011 Lift Pu=p Off 0722.01 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 132 011 Lift Pu=p on 0724.03 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> 132 Reactor Coolant ?u=p Off 0724.29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> 132 011 Lift Pump Discharge Low  ;

0726.03-hours 132 Reactor Coolant Pump Zero Speed i 0725.21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> 132 011 Lift Pump Off As closely ac can be deter =ined the fire alar = sounded at approximately 0725 hours0.00839 days <br />0.201 hours <br />0.0012 weeks <br />2.758625e-4 months <br />.

An operator was dispatched to the Reactor Building and he i==ediately confir=ed to the Control Room the presence of smoke in the-Reactor Building. Additional operators were dispatched to locate and contain the fire. Fire was observed both at the bottom of the 28-inch J-leg fro = the 13 Stea= Generator to the 132 Reactor Coclant Pu=p, and in the vicinity of pu=p casing. Carbon dioxide was utili:ed to extinguish the fla=es and prevent an i==ediate recurrence of the fire. The tury Supervisor

-notified the Station Superintendent at approni=ately 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br />.

Cooldown of the Reactor Coolant Systa= was initiated shortly after 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> in

. order to ' reduce the t =perature of the system below the- flash ' point of the leaking oil. . Personnel observed oil flowing from the vicinity of the icwer bearing housing.

. A hose van attached to this housing and oil was drained to dru=s placed in the bottom of the. Reactor Building in order to reduce the source'of oil for potential

-ignition.

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11e Oconee County Rural Fire Frotection Association had been contacted. and sent i personnel and equipment to standby if required. Station personnel, however,

• extinguished the fire and prevented its reeverence; consequently the Association's assistance was not necessary. -The Station Superintendent advised the Atomic Energy Commission, Directorate of Regulatory Operations, Region II, of the incident at approximately 0845 hours0.00978 days <br />0.235 hours <br />0.0014 weeks <br />3.215225e-4 months <br /> on December 30,1972.

After the loop had cooled down sufficiently to preclude the possibility of additional ignition, all Mirror insulation was removed from the pump casing and the 28-inch J-leg between the pump casing and steam generator. Some oil had run.across a seismic restraint to the steam generator and a portion of the insulation was' removed from the steam generator to determine the extent of oil in.

this area. The pump aotor, pump casing, steam generator and associated piping were thorcushly cleaned to remove-any deposits which.might prove deleterious in the future. Several pieces of. insulation were flushed with domineralized water to

. determine the extent of oil between the-layers of the Mirror insulation. It was ,

determined that oil between the insulation layers was insignificant and would cause no problems upon reheating of the Reactor Coolant System.

A representative of the Diamond Power Specialty Corporation, Mirror Insulation Unit, inspected the insulation involved and determined that it was not functionally affected and that discoloration due to smoke would not affect the efficiency of -

the insulation. L representative of Westinghouse Electric Corporation inspected

the pump casing, obtained samples of the residue for future analysis and indicated that there were no problems resulting from the fire. No the;=al discoloration was observed on-the pump casing or inlet piping. l Following reinstallation of the removed insulation, and perform

• ance of necessary repairs, repressurization of the system began during the evening shift (1600-2400 hours) on January 1, 1973. Hot lunctional Testing was completed and no further . abnormalities have been determined to this point.

Subsequent to the occurrence of the fire, the chemical analysis of the oil involved was checked with the manufacturer of the oil. The =anufacturer stated that the oil contained no halogens or heavy metals. Chemical analyses of residue has deter =ined halogens to be present in negligible concentrations, well within permissible limits.

.3.0AMALYSIS AND CORRECTI7E ACTION Reactor coolant pump motors were initially shipped with a 1/16" asbestos sheet gasket installed in the flanges of the oil lift pump circuit. However, the oil lift pump discharge lines had been dismantled on all four (4) pu=ps to permit installation of seismic rescraints nearby' . Reassembly was done by a vendor serviceman with Vallumoid~ gaskets and it-is believed'that one (1) bolt was insufficiently torqued.

-Folicwing this incident the Vellumoid gaskets were removed from the high pressure flanges on each reactor coolant pump motor and were replaced in 1/16" Johns-Manville

' Style 60 graphitedLasbestos sheet packing'.m Additionally, the overflow line from the upper oil reservoir to the lower oil reservoir was broken and connected-by means of a temporary _ hose to a drma located in the Raactor Building basement.

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Westinghouse is'.to furnish new flanges, utilizing a recessed 0-ring seal, and will provide-instructions concerning 0-ring material and proper torquing. The temporary overflow line will be per=anently piped to prevent recurrence of a fire in tha event a gasket failure.should occur. Similar modifications will be made on Units 2 and 3 prior to initial operation of the reactor coolant pump motors on these units.

4.0 SAFETY IMPLICATIONS The fire which occurred as described herein was promptly detected and controlled.

Had the reactor been critical the incident would not have hindered the safe shutdown'of the reactor. The corrective actions detailed above should prevent any recurrence of this incident. The safe operarion of the unit was not, and

- should not ba in the future, adversely affected by this occurrence.

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